Understanding Statistical Process Control

Statistical quality control (SQC) helps track and
improve product or service quality. Statistical process control
(SPC) is the primary tool of SQC and encompasses the collection,
arrangement, and interpretation of process variables associated
with a product, in regard to uniformity of quality.

Every process is subject to variation and
therefore there is always room to improve process consistency and
quality. To respond to this, adopt a continuous improvement
strategy. By repeating the following cycle, a strategy of
prevention can be implemented. This is the key to using SPC
effectively. Consider the following steps:

Analyze the process

What do we know about the
variability of this process?

Is this process statistically
controllable (predictable)?

Is the process capable of meeting
the set requirements?

What considerations are most
important to meeting process quality criteria?

Maintain (control) the
process

Improve the process

SPC encompasses the concepts of variation,
statistical control, and process capability, and typically uses the
tools XRS control chart, capability chart, and the Pareto
chart.